Brain surgeries are becoming an increasingly acceptable therapeutic and diagnostic modality in the neurosurgical treatment of patients suffering from chronic pain, Parkinson's disease, seizure, and other medical conditions. Among brain surgeries, brain biopsy is a common diagnostic surgery. A brain biopsy is the removal of a small piece of a brain tissue for the diagnosis of the brain abnormalities. A brain biopsy is generally used to diagnose Alzheimer's disease, tumors, infections, inflammations, and other brain disorders. By examining the tissue sample under a microscope, the biopsy sample provides the doctors with the information necessary for diagnosis and treatment. Generally, biopsy surgeries are categorized based on the technique and the needle size used for tissue extraction. A stereotactic biopsy, otherwise known as a core biopsy, is one of the least invasive types of biopsies. In a stereotactic biopsy procedure, 3-D imaging technology, as well as data from CT (Computer Tomography) and MRI (Magnetic Resonance Imaging) scans, are utilized to examine a sample from a tissue such as a brain tissue. Images that are taken in at least two planes may be used to pinpoint a tissue location (hereinafter referred to as a target), such as a tumor or microcalcifications in a breast. The pinpointed location may be used to help guide the tissue removal procedure. In a stereotactic biopsy procedure, the underlying principle of parallax may be utilized to determine the depth or “Z-dimension” of the target.
During different surgical procedures such as biopsies, and especially for stereotactic biopsies, some visual information may be simultaneously provided for the surgeon in real-time. One method that uses visual information includes detailed information of the 3D path the surgeon must pass in order to perform the biopsy, as well as the surgical instrument's tracking information. Facilitating the use of visual information and real-time tracking of instruments during the surgical procedures can help enhance the precision and quality of the surgeries.
In addition, stereotactic brain biopsy systems are also categorized based on the mechanism used to secure and position the biopsy device. A frame-based stereotactic biopsy system is considered the industry standard for evaluation of histological specimens from targets within the brain. For example, a frame-based stereotactic brain biopsy system requires attachment of a frame to the skull of a patient to assist the surgeon in locating and collecting a sample from a specific target within the brain. In this case the patient requires anesthesia during the procedure. Generally, the frame is attached to the patient by invasively inserting four screws into the skull. This frame-based method can provide the neurosurgeon with a generally safe and effective means for performing a biopsy retrieval.
However, the frame-based head fixation can be painful and the head movement limitation can be intolerable to many patients. Furthermore, there may be a risk of epidural hematoma, cranial fracture, and cerebrospinal fluid (CSF) leakage following the application of head pins, as well as lacerations of the scalp with patient movements, especially in young children. From the surgeon's perspective, rigid head fixation may also be problematic since the head pins are bulky and limit intraoperative flexibility as well as free movement of the surgical instrument. If the patient's head moves relative to a reference arc, the accuracy of the system is greatly reduced, potentially compromising successful execution of the procedure.
A frameless stereotactic biopsy procedure is a minimally invasive biopsy procedure, where the biopsy device is mounted on a Mayfield and the biopsy procedure performed under image guidance obtained from sectional imaging devices such as ultrasound/CT scan/MRI scan and other such imaging systems. Image guidance is required to select a least harmful path for the biopsy needle, so as to avoid vital organs and structures such as blood vessels or other sensitive regions. The needle may be positioned manually at an approximately correct angle/position by trial and error. In some cases this may be better carried out by using needle guiding devices that can guide the needle in the precise direction so as to reach the target point in the brain. The frameless stereotactic biopsies, generally, are integrated with an “end-effector” that is responsible for precisely guiding the needle.
However, in frameless brain biopsy procedures, fine positioning of the end-effector has been associated with challenges. For example, once the fine positioning of the end-effector is done, a locking mechanism is required to fix the end-effector at its position. Generally, fixing the end-effector of the frameless brain biopsy device is effectuated by tightening one or more screws. Tightening screws of the frameless brain biopsy device may displace the fine-positioned end-effector and consequently degrade the accuracy of the frameless brain biopsy procedure. In addition, the fixation of the frameless brain biopsy device screws is accomplished through a trial and error procedure that may substantially affect the cost, accuracy, and efficacy of the frameless brain biopsy procedure.
There is, therefore, a need in the art for frameless stereotactic biopsy systems and devices in which the fine positioning is accomplished more accurately and more easily without resorting to an inaccurate and time-consuming “trial and error” procedure.